Any tips on how to remove the pressed in ball bearings from the crank journals. I've managed to do it on my existing crank but it's taken me 4-5 hours all up to get the 4 out. I've destroyed a center punch, a couple of punches and about 20 drills in the process.

I've tried drilling them out on a milling machine with cobalt drill bits (worked for one, but I think I work hardened the second and it took massive effort and a bit of damage to the surrounding crank to get it out, not to mention a whole stack of 1/8ths drill bits.

I've tried grinding off the surrounding metal tab and half the bearing then rotating it and grinding it some more. This worked for 2 but one got stuck and ended up jamming into the journal. After around 2 hours of work I ended up punching it through to the center of the big end then out one of the bearing journals.

There must be a better way... Is there an arc process or something to blast them out? Any ideas? What about a small hole drill that can go around the ball?

 

what the hell is this guy talking about

 

I'm referring to the oil passages in the crank that connect the oil feed to the main bearings to the big end bearings. These are sealed off with a ball bearing in the factory that is stamped into the oil journal. Old cranks build up a lot of gunk where the hole is drilled past the big end bearing and it's very hard to clean out well, even with a 90 degree spray nozzle. For race engines, it's best to remove the ball bearings so that you can clean all the gunk out of the crank oil passages and then tap and sealed with a 1/8npt plug and some loctite. My current crank is converted in this way.

You'd only bother to do this for a race engine, which is why I posted in the race prep forum. I'm doing it because I'm currently machining my crank and cleaning out these journals is going to be important due to risk of metal shavings getting in there. On this crank, there is around half an inch of black crud in each oil passage once the ball bearings are removed.

 

My local race engine builder uses a thin tube to get to the bottom of the blind passage and shoots a cleaner and compressed air from the end of the passage out but does not remove the palls plugging it, he does removes the oil galley cap on the back end of the block for cleaning.

 

Use these, they even work in a drill press. A La AvE to remove broken taps...

 

Try a solid carbide drill bit. Or if you have a milling machine, you can plunge cut with a carbide end mill. Carbide should work much better on the hardened ball bearing. Take your time though... carbide is brittle, and if you break the drill/endmill off in the bearing you'll have a hell of a time getting it out.

 

Weld a pin to it and pull it out with a slide hammer.

 

ball bearings?

 

 

Wow that's bizarre and neat at the same time. Cost saving measure by Mazda or?

 

The majority of cranks have them.

 

Thanks for all the tips... I'll have a look around for some appropriate carbide tools. Does anyone know about using anodes to burn out bearings? I've head of it before but I have no idea what the technique even is.

I prefer to remove the ball bearings as even spraying in there is hard to remove the junk. On some cranks it's a really bad thick sludge that won't come out with any degreasing. Once the ball bearings are removed, it's easy enough to clean up the hole and tap. And then any future work on the engine the bungs can be removed and the crank cleaned.

The carbide bits look like the go. I managed to get out one ball bearing with a dremel and a small grinding bit, but I think the right carbide cutter on a mill would work good as long as the bearing doesn't spin in location.

This sort of drilling needs to be done on a mill. I managed to do it with a hand drill on one bearing but I bruised my shoulder and snapped a few drill bits. Chances of injury or damage to the crank are high so a milling machine would be a requirement.

 

First i start with a stubby ball end carbide burr and grind out the area where the factory has steaked the ball into the crank and then make a flat surface on the ball.

Then i use a stud welder and weld a stud to it and then pull it out with a slide hammer. takes about 15 mins to do all of them on a miata crank.

 

awesome... sounds like the best option and obviously works. Thanks Twibs... exactly what I was looking for. I'll give that a go on my next crank.

 

I'm used to V8 stuff, the cranks are a little different.

 

I was raised on small block chevys, and come to think of it, they dont have any holes to seal(iirc), they just drill from journal to journal i guess.

 

My remanded crank came with these drilled out and threaded plugs installed with loctite if I recall... It was 10 years ago when I built it

 

On a cross-plane V8 crankshaft you can't drill all the way through like you can on a 4-cylinder crank when connecting 1-2 and 3-4, but you still need to start the drill externally from the crankshaft, and you're still going to need to plug that hole afterwards. Unless V8 cranks are cast using sand to make the internal journal passages?

--Ian

 

The V8 cranks typically just offset drill from main to rod to rod to main and the crank end(s) is freeze pluged.

 

And some dont even need plugs on the ends.

Found some interesting stuff on google.